Control of refrigeration



p 1950 A. B. NEWTON 2,521,247

CONTROL 0E REFRIGERATION Filed Jan. 13, 1941 4 Sheets-Sheet 2 filled/{ ke ATTORNEY P 1950 A. B. NEWTON 2,521,247

CONTROL OF REFRIGERATION Filed Jan. 13, 1941 4 Sheets-Sheet 3 Alwim '8. Nawirom 35 A ATTORNEY Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE CONTROL OF REFRIGERATION Alwin B. Newton, Minneapolis, Minn, assignmto Minneapolis-Honeywell I Regulator Company, Minneapolis, Minn, a corporation of Delaware Application January 13, 1941,"Sci'lal No. 374,179

This invention relates to'the'cjontrol of re-- frigerating systems, particularly those of the compression type.

The object of my invention is to provide improvements in the manner and means of controlling the compressor, the control being in response to evaporator, temperature or suction pressure, the temperature or other condition of the air in the refrigerated space, and head pressure. The invention may be applied where the source of refrigerant is other than a compressor.

Controllers have heretofore been proposed which provided for cycling the compressor from evaporator temperature or pressure, the compressor preferably being started at an evaporator temperature high enough to insure defrosting thereof. It is an object of my invention to provide improved means in conjunction with such a controller to prevent operation'of the compressor whenever the temperature of the refrigerated space is at the desired value.

It is also an object of my invention to provide a modified arrangement whereby'the compressor can be started when the refrigerated space requires cooling even though the evaporator temperature has not risen to a given value.

Another object of my invention is to provide I an improvement for controllers of the type referred to in the foregoing object embodying a. normally inactive device responsive to the temperature of the refrigerated space which acts to change the setting of the controller when the temperature of the refrigerated space is satisfactory so as to keep the compressor out of operation or to permit it to operate at higher than normal evaporator pressures.

More specifically, an object of my invention is to provide a compressor controller responsive to evaporator temperature or pressure embodying a switch, switch operating means and an attachment comprising a normally inactive device which in the preferred form of the invention is an electromagnetic device responsive to temperature of the refrigerated space for acting on the switch operating means either to keep the switch open in'one form of the invention, or to independently close it in a modified form of the invention.

' Another object of the invention is to'provide a controller generally as described in the foregoing object having improved structural forms and arrangements whereby the switch can be controlled from evaporator temperature or suction pressure, the space temperature and discharge pressure of the compressor.

s cla ms. (01. 62-4) Another object of my invention is to provide a compressor controller embodying a switch operating arm, a device responsive to suction pressure for moving the arm and an electromagnetic device responsive to the temperature of the refrigerated space operative directly on the arm for either keeping the arm in switch open position or for moving the arm to closed position of the switch.

Another object of my invention is to provide a compressor controller having a suction pressure responsive device for closing a switch and an attachment responsive to space temperature embodying a spring normally held in an inactive normally inactive means operative in response to the space temperature to act on the whifiletree, or more directly on the operating means of the switch of the controller to keep the compressor out of operation or to materially raise the evaporator pressures at which it is started and stopped.

The improved structural forms and arrangements of my invention, the details of which are described in the following specification constitute further objects of my invention.

In the annexed drawings:

Figure 1 represents a compression "type' refrigerating system showing the details of a controller with space temperature responsive attachment constituting one form of my invention.

Figure 2 is a view taken along line 2--2 of Figure 1.

Figure 3 is a view of modified form of controller having an attachment arranged to act in a manner reverse to that of Figure 1.

Figure 4 is a view of another modified form of controller.

i ure 5 is a view of another form of controller with direct acting space temperature responsive attachment as in Figure 1.

Figure 6 is a view of another form of controller with direct acting relay attachment.

Figure 7 represents a known form 01' comfrom the bottom of the casing 28.

and It designate bolts which extend through the 3 pressor controller with a space temperature responsive attachment for changing the setting or the controller.

Figured is a diagrammatic View of a modified form of controller with space temperature responsive attachment for changing the control setting of the controller.

Figure 9 is similar to Figure 8 but representing a modified form of controller.

Figure 10 is similar to Figures 8 and 9 but representing a further modified form of controller.

Referring to Figure 1 of thedrawings, a reirigeration system oi the compression type is shown,-the system having a compressor motor controlled by a controller constituting a preferred form of my invention. Numeral ll designate! the compressor, driven by an electric motor II by means of a belt II. The compressor ll discharges into a condenser I! through a pipe ll and the condenser II is connected to an expansion valve II by a pipe it. The expansion valve It has its outlet connected to an evaporator l.'| disposed within a compartment to be refrigerated, II. The outlet of the evaporator I1 is connected to the suction side of the compremor by a pipe It. The expansion valve II is of the usual superheat control type which is operated in response to the temperature of the refrigerant at the outlet of the evaporator as well as in response to evaporator pressure, the expansion valve including a thermal bulb lladiaeent to the outlet of the evaporator connected to a pressure chamber within the expansion valve by a capillary tube 23.

The controller of my invention is indicated generally by thereference character 2', and it comprises a generally rectangular metal casing 28,asmaybeseenonl"igures1and2.thecasing having flanged openings 21 and llinits opposite sides through which electrical leads pass to the interior of the casing.

Within thecasingflisahorisontalahelfil having a vertical portion II, the shelf 2. being supported by standards ii and 32 upstanding Numerals ll standards II and 32 and which engage the shelf II in screw-threaded relationship. Supported on theshelilsisasnapswitchilwhichisotthe same type disclosed in detail in Patent 2,318,734, issued May 11, 1943, to Albert E. Beak. The snap switch 31 is enclosed within a Bakelite housing and has "on" and oii'"'positions and is of the type which tends to remain in the position to which it is operated. The snap switch 31 has an operating stem at extending downwardly The housing II is flanged and the title asidewallofthecasingflandwhichisrotatabk byamanualknobfloutsideofthecaaing. Adja- The bellows within housing 4| is expansible and centtbeknobtlisagraduateddialllmovahle withrespecttoanindexmarkerforindieating thepositionofthecamll. 'lhecamltls mountedonashattwhiehextembthrwlhaaide walloftheeasingflandwhichhrotatablebya, manualknoblloutsideotthe isagraduateddialllsimilarto themanualknobll.

Irom the foregoing it will be ieverflisanoatingleverandthatits moves between the cams l2 and" which act v l tion, the circuit for the completed as follows; from a line mm thereshouldbeariseinsuctionpreasurewheh thesnapswitchiscloeed.asdescrihed,andthe leverl'lmayberaisedandloweredbyrotatlng theam. After-thecompreasorhasstartedin spiral contour as pointed out above, that is, the point at which the lever 41 engages the edge of the cam may be raised and lowered by rotatably adjusting the cam.

The shop switch 81 may also be operated by a device responsive to the discharge pressure of the compressor. This device includes an expansible and contractible bellows encloud within a housing 88 which has a flange secured to the lower side of the casing 28 by screws 88 and 51. The

charge pipe I4 of thecompressor by a tube 88. .The bellows within housing 85 operates a bellows post 88 which extends through a nut 18 inside of ber which has upwardly bent cars so disposed as to reduce the magnetic spacing between the g lingers 8i and 82 and the adjacent portions of the slots in which they engage. The magnetic circuit of winding 88 is of course formed by the frame 84 including leg 81, the hinge member 83 and the core 88. Secured to the hinge member 88 10 by means of a bolt 88 is an arm 81 which is spaced bellows within housing 85 is connected to the disfrom the hinge member 88 by the brass plate member 85. The portion of the arm 81 to the left of the plate member 85 is held in spaced relationship to the hinge member 88 by a screw 88 carrythe casing 28. Numeral II designates a small lngalock nut adjacent the arm 81. The left end of lever having ears pivotally e sasins a pin 12 ex- .tending outwardly from the back of the casing 28. Numeral I8 designates a spacer member between one of the said ears and the back' of the casing .28. The right end of the lever 1| is engaged in the other of the slots in the operating stem 28, and the left end of the lever 1| may be engaged by a screw-threaded member 14 carried by the end of the bellows post v68. That is, when the compressor discharge pressure increases to a predetermined relatively high value, the bellows within housing 65 expands moving member 14 into engagement with lever 1I causing lever H to V rotate clockwise so as to move operating stem 38 downwardly for opening the snap switch 81. The snap switch may be thus opened even though the suction pressure is at a value at the time to have the switch closed. That is, the strain release connections between bellows post 44 and lever 41 will permit the operating stem 38 to be moved downwardly by the discharge pressure responsive device even though the lever 41 is engaging cam 52 at the time, the leaf springs 48 and 48 permitting relative movement of the lever 41 and the ball 46 as pointed out above.

The structure so far described has heretofore been used in the art for controlling a compressor in response to suction pressure and head pressure. My invention comprehends employing an additional device in conjunction with the controller whereby the compressor is controlled in response to the temperature within the refrigeratd compartment as well.

Referring to Figures 1 and 2, numeral 11 designates a bracket secured to the vertical portion 88 of shelf 28 by screws 18 and I8. The bracket 11 has an angular portion 88 adjacent to the side wall of the casing 28 which has an opening to which is secured a flange on the flanged member 28 through which electrical leads are carried to the interior of the casing. Bracket 11 also has an angular portion 82 forming a projection extending outwardly and away from the casing 28 and the end of which is bent upward slightly, as may be seen on Figure 2. Secured to the portion 82 by a screw 83 is a frame 84 made of magnetic material and forming part of an electromagnetic device designated generally at 85. The frame 84 device designated generall at 85. The frame 84 has legs 88 and 81 disposed on opposite sides of a winding 88 within which is a core, the core and winding being held in place by the screw 88. The core is of the split pole type, a shaded portion being designated as 88 and the other portion being designated as 88'. Numeral 8| designates a shading coil engaged on the core portion 88. The leg 81 has two downwardly extending fingers 8i and 82 which engage in grooves or slots in a hinge member 88. The fingers 8| and 82 and the grooves in which the arm 81 extends inwardly toward the interior of the casing 28 and normally is disposed in a posin tion just above the right end of lever 41 adjacent the operating stem 88. That is, the winding 88 of the electromagnetic device 85 is normally energized with the hinge member 88 and arm 81 in the position shown in Figure 2, the hinge member 83 forming an armature which is held against the core 88. The right end of the arm 81 cf:-

tends to the right beyond leg 81 of frame 84, as

may be seen on Figure 2. A coil spring 88 is attached to this end of the arm, the other end of the coil spring 88 being attached to the right end of bracket portion 82 so as to normally urge the arm 81 and hinge member 83 in a counterclockwise direction, that is, toward deenergized position of the electromagnetic device. The right end of bracket portion 82 is spaced from the frame 84 by means of a screw I88 carrying an adjustable 5 nut I8I whereby the spacing of the end of member 82 from frame 84 and consequently the tension of spring 88 may be adjusted.

The electromagnetic device 85 is controlled by a thermostat I83 disposed within the refrigerated ,4; compartment I8 so as to be responsive to the temperature of the air therein. The thermostat I83 comprises an expansible and contractible bellows I84 having an operating stem engaging a pivoted lever I85 carrying a mercury switch I88.

The lever'I85 is normally urged in a counterclockwise direction by a coil spring I81. The electrodes of the mercury switch are at its right end, and when the temperature within the compartment I8 is above a predetermined value, the

bellows I84 is expanded so as to rotate the lever 185 to a position wherein the electrodes of the mercury switch are bridged, as shown in Figure .1. Whenever the mercury switch I86 is closed the winding 88 of the electromagnetic device is energized through the following circuit:

from line conductor 68 to mercury switch I86, through wire I88, winding 88, and back to the line conductor 84. Thus, whenever the temperature within the compartment I8 is above a pre- 00 determined value high enough to indicate that refrigeration is required, the electromagnetic device 85 is energized and the arm 81 is held in a normal and inactive position. Under these circumstances the compressor is controlled by the 85 suction pressure responsive mechanism which operates to start the compressor at a predetermined relatively high suction pressure which is preferably above the melting point of water to insure that after-each cycle of operation of the 10 compressor the evaporator I1 will be defrosted before the compressor is again started. Thus the compressor is normally cycled in the manner just described. If, however, at any time the temperature within the refrigerated compartment they engage form a pivotal connection between 15 I8 falls to a predetermined low value at which the 7 bellows IN is contracted suiiiciently to move the lever It! in a counter-clockwise direction so as to open the mercury switch I", the electromagnetic device II is deenergized. when the device II is deenergized, the coil spring ll rotatesthe arm 81 in a counter-clockwise direction bringing its left end into engagement with the operating lever ll moving the said lever downwardly, that is in a clockwise direction. so as to move the stem 38 downwardly to open the switch 81. If the switch 31 is already open at the time the electromagnetic device II is deenergized, the left end of arm 91 will engage lever 41 and hold the switch in an open position. When the electromagnetic device 85 is thus deenergiaed, even though the suction pressure rises to or above the value at which it normally closes the switch 31, the switch 31 will remain open. However, if the suction pressure should rise to a relatively. high value which.- may be, for instance, ten pounds higher than the value at which suction pressure normally closes the switch 31, the lever 41 will be rotated in a counter-clockwise direction nevertheless, carrying the arm 01 upwardly with it so as to close the switch I! irrespective of the electromagnetic device Ii. The pressure at which the suction pressure responsive device will close the switch 31 when the electromagnetic device '5 is deenergized may be adjusted by adjusting the tension of spring II, which determines the amount of loading which is placed on lever 41 when the electromagnetic device 85 is deenergised. The head pressure responsive device may of course open the switch 31 at any time that the head pressure or discharge pressure rises to an excessive value.

From the foregoing it will be understood that with the control arrangement of Figures 1 and 2, the compressor is controlled normally in response to suction pressure and that the arm '1 is normally held in an inactive position having no eflect on the control of the compressor except when the thermostat It: moves to a satisfied position. The arm 91 then moves downwardly engaging the lever 41 so as to open the switch 31 if it is closed or to hold it in an open position if it is already opened. The arrangement, therefore, provides for eliminating unnecessary operation of the compressor. That is, the compressor is controlled in a normal manner from suction pressure, but whenever refrigeration is not required the controller is prevented from functioning in its usual manner. The controller itself without the electromagnetic device is a unitary instrument which may be used without the electromagnetic device. The electromagnetic device forms an attachment which may be fastened to the controller and operated in conjunction therewith merely by means of securing the bracket 11 to the vertical portion 8. of the shelf 2! by means of screws as pointed out above, that is, the electromagnetic device forming the attachment may be very simply applied to controllers already in use on installations. when the electromagnetic device or attachment is fastened in position, the arm .1 assumes its proper position with respect to the lever ll. when the attachment is applied to controllers which have previously been installed, a special cover is used for the casing of the controller, which cover is so formed as to house the electromagnetic attachment as well.

Referring to Figure 3 of the drawings. this figure is a view of a slightly modified form of controller, this view being very similar to Figure vious embodiment,Iprefer to refer to'as direc acting, while in the present embodiment of the invention I have provided an electromagnetic attachment which I refer to as being a reverse acting attachment. Most-of the parts of Figure 3arethesameaspartsshownin1'1gure2and are numbered the same. In Figure 3, however. the bracket "2 which is attached to the vertical portion SI of the shelf 2! is slightly different in not having its end extended for attachment of the spring ll thereto. The spring I is attached at its upper end to an ear III on the frame N. The hinge member 08 has attachedthereto a bracket member I having a pair of downwardly extending ears to which are pivoted correspondingearsonanarmlll correspondingtothearm ll of the previous embodiment. The lower end of spring II is attached to bracket III. A bolt I22 extends through the hinge member '3 and throughthearmflltherebeingacoilspring I28 encircling the bolt between the arm "I and a 7 pair of nuts on the end of the bolt. The spring m exertsapressureonthearmlfl urgingitina clockwise direction.

The thermostat"! of the present embodiment is the same as in the previous embodiment and is connected to the winding of the electromagnetic device II in the same manner. In the pruent embodiment. the arm I" has its left end disposed underneath the lever 41 adjacent the operating stem 38 of the snap switch 31. The electromagnetic device OI in the present embodiment is energized whenever the thermostat I is in its hot position as shown. Under these circumstances the hinge member It and arm "1 are in the positions shown in Figure 3 with the left end of arm I" holding the lever 41 in a raised position so that the snap switch I! is closed. In other words, in the present embodiment whenever the thermostat is not satisfied, that is when there is a demand for refrigeration, the electromagnetic device moves the switch I! to closed position for starting the compressor. Obviously the operation of the present electro-magnetic device is asentially opposite to that of the modification of Figures 1 and 2. In the present embodiment the snap switch 31 may be opened by the head pressure responsive device even though the switch has been closed by the electromagnetic device. That is,iftheswitchisclosed,withthepartsinthe position shown in Figure 3, the head pressure responsive device may move the operating stem ll of the snap switch downwardly, moving the arm "I downwardly at the same time, the coil spring I28 forming a strain release mechanism permitting the arm 3" to be moved downwardly even though the electromagnetic device II is energized. In the present embodiment,-when the thermostat is in an unsatisfied position, the switch 31 normally remains closed with the compressor in operation even though the suction pressure falls below the value at which the switch is normally opened in response to suction pressure. However, if desired the spring III may be adjusted so that the switch I! will be opened'at a lower than normal suction pressure when-the electromagnetic device is energised. As shown, the electromagnetic device may be enclosed within a suitable housing Ill which may form part of thecasingfl ormayformpartofacover fcrthe casing 20.

ReferringtoFigme4o!thedrawings.Ihave shownafurthermodifled formofmyinventicn having a dlrect acting electromagnetic attach- 2. Theelectromagneticattachmentofthem-Iimentasistbeattachmentoftheembodiment of Figures 1 and 2. Many of the parts of the embodiment of Figure 4 are the same as parts of the embodiment of Figures 1 and 2 and are numbered the same. In the present embodiment. the bellows within housing 4I actuates a lever I25 which is pivoted ona pin I23. The bellows post 44 is connected to the lever I25 by a strain release mechanism which is the same as that of the embodiment of Figures 1 and 2. The lever I23 has an ear at its right end which is pivoted to a corresponding car on the lever 421 by a pin I21. In the present embodiment, the snap switch 31 has an operating stem 433 having a slot'therein through which the lever 421 extends. The right end oi the lever 421 is disposed between two cams 52 and 53 which are the same as the cams of Figures 1 and 2. The left end of the. lever 421 has an ear which is pivoted to a corresponding ear on the end of an operating stem I23 by means of a pin I23. The operating stem I23 is connected to the armature of an electromsgnetic device within a housing I23 which has aiiange secured to the lower part of the casingf423, by screws I33 and III. The electromagnetic device is controlled by a thermostat I33 which is the same as that of previous embodiments and which energizes the electromagnetic devicewhen the thermostat is in a satisfied position. With the parts in the position shown, the thermostat is not satisfied and the electromagnetic device is deenergized. Under these circumstances the switch 31 is controlled by suction pressure. Upon a rise in suction pressure,

the bellows within housing 4I expands moving bellows post 44 and lever I25 upwardly, the lever I25 moving in a counter-clockwise direction and also moving lever 421 in a counter-clockwise direction. Lever 421 moves relatively freely with out moving the stem 433 until its right end engages the cam 52, the stem I28 being freely reciprocatable at this time as pointed out below. Upon this occurring, further upward movement imparted to lever 421 by lever I25 causes lever 421 to pivot in a clockwise direction about cam 52 which acts as a fulcrum, this action moving the stem 433 upwardly to close the snap switch 31. Upon a fall in suction pressure to a predetermined relatively low value, the bellows with-- in housing GI moves the post 44 downwardly.

moving lever I25 in a clockwise direction and moving the right end of lever 421 downwardly until said end engages the lower cam 53. Further downward force exerted on lever 421 causes it to pivot in a counter-clockwise direction about cam 53 which acts as a fulcrum, this action moving the stem'433 downwardly and opening the snap switch 31. During the above described opening and closing operations of the snap switch 31, the left end of lever 421 moves up and down relatively freely because the electromagnetic device within housing I29 is deenergized and very little effort is required to move the armature attached to the stem I23. In the event of the thermostat I03 becoming satisfied, however, and closing the mercury switch I33, the electromagnetic device becomes energized attracting its armature and moving the stem I23 downwardly. Upon this occurring, the left end of lever 421 is moved downwardly suiiicientiy to move the stem 433 downwardly so as to open the switch 31. If the switch 31 is closed at the time the electromagnetic device is energized, the switch is opened, and if it is already open, it is held in the open position as in the embodiments of Figures 1 and of system as completely magnetic device is energised. even if the right endof arm 421 is enga i g cam 52, the downward movement of the left end of lever 421 is permitted by reason of the strain release connections between bellows post 44 and lever I43, the lever 421 pivoting in a counter-clockwise direction, under these circumstances, with the cam 32 acting as a fulcrum.

-It will be understood of course that the controllers having modified forms as shown in Figures3and4aretobeusedinthesametype shown in Figure l, and the thermostats of Figures 3 and 4 are to be disposed in refrigerated compartments as shown in Figure l.

Referring to Figure 5 d the drawings, I have shown a form of controller of a somewhat different type with the electromagnetic attachment of previous embodiments applied thereto for holding the switch in its oif position when there is no demand for refrigeration, the switch of course normally being controlled by suction pressure. The controller of Figure 5 comprises a casing I35 within which is a housing I33 containing a bellows to be connected to the suction pressure line of a refrigerating compressor. The bellows operates a bellows post I31 having a pointed end engaged in a suitable seat on the end of an operating lever I33. The lever has a crimped portion I 33 which engages a knife-edge formed on a member I43 mounted within the casing so that the lever I33 may pivot about the member I43. The left end of the lever I33 is attached to the operating stem I of the snap switch 31 of the same type as that of the previous embodiments. Numeral I42 indicates a coil spring, the lower end of which is attached to an ear on the lever I33 and the upper end of which is attached to a member I43 engaged in screw-threaded relationship with a screw I44 adjustable from outside of the casing I35. The spring I42 urges the lever I33 in a clockwise direction, and its tension is adjustable by adjusting the screw I44. Numeral I45 indicates a lever of the whiiiietree ype, the right end of which is disposed between two projections I43 and I41 forming part of a bifurcated member I43 mounted within the casing I35, the projections I43 and I41 forming stops for the end of the lever I45. The other end of the lever I45 is disposed between two similar projections I43 and I53 forming stops, these projections forming part of a similar bifurcated member III mounted within the casing I35. The mid point of the lever I45 has a knob I53 which normally engages an abutment I54 on the operating stem I of the switch 31. Numeral I55 designates a coil spring, the lower end of which is attached to an ear on the lever I45 and the upper end of which is attached to a member I53 engaged in screw-threaded relationship with a screw I51 adjustable from outside of the casing I35. Numeral I53 designates a similar coil spring attached to an ear on the opposite side of the knob I53 of lever I45, its upper end being attached to a member I53 engaged in screw-threaded relationship'with a screw I33 adjustable from outside of the casing I35. The spring I53 is some- 7 what stronger than the spring I55 for purposes which will now be described.

When the suction pressure is low, the bellows within housing I33 will be contracted, and under these' circumstances the coil springs I42, I55 and I53 will hold the lever I33 in a clockwise 2. If the switch 31 is closed when the electrorotated position and the whiiiietree I45 a posi- 11 tion with both its ends engaging the upper stops I45 and I45. With the parts so positioned, the operating stem I4I of the switch 51 will be in its upper position with the switch 51 opened, the switch 51 being open when the stern I H is pushed upwardly in the present embodiment. As the suction pressure rises, the bellows within housing I55 will expand rotating the lever I55 in a counter-clockwise direction against the bias of spring I42. The left end of lever I55 will move downwardly pulling the stem I4I downwardly and also the whiilietree I45. As the left end of lever I55 moves downwardly, the left end of whiflietree I45 will first move downwardly from stop I45 to stop I55 inasmuch as spring I55 is the weaker of the two springs attached to the whiiiietree. Such movement, however, is insumcient to close the switch 51 inasmuch as operation of the switch requires a relatively large movement necessitating that both ends of whiiiietree I45 be in engagement with the lower stops before the switch is closed. As the suction pressure continues to rise, lever I55 will move the right end of whiifietree I45 downwardly from stop I45 to stop I41, and when this happens the stem I will be actuated to close the switch 51.

From the foregoing it will readily be seen that the suction pressure at which the switch closes is dependent upon the adjustment of spring I55 because the adjustment of this spring determines the suction pressure at which the right end of whifiietree I45 moves downwardly from stop I45 to stop I41. When the compressor is started by reason of closure of switch 51, the suction pressure will fall causing the bellows within housing I55 to contract permitting lever I 55 to move in a clockwise direction. The right end of whimetree I45 will now first move upwardly from stop I41 to stop I45, but such movement will not be enough to open snap switch I51. As the suction pressure further is reduced. the left end of whimetree I45 will move upwardly from stop I55 to stop I45 causing the switch 51 to open. Ob-

viously, therefore, the pressure at which the switch opens is dependent upon the adjustment of spring I55. It is to be seen therefore that separate adjustments of the cut-in and cut-out points of the switch are provided by the arrangement of the controller of the present embodiment. By adjusting the spring I42, both the cut-in and cut-out points of the switch may be varied.

In the present embodiment of the invention, I have shown a particular manner of applying the relay attachment of the previous embodiments so as to hold the switch in its off position when the thermostat is in its satisfied position. Numeral I54 designates a fixed member mounted within the casing I55 which supports the electromagnetic mechanism I55 comprising a winding and a core member, the winding being arranged to attract an armature formed on the end of a lever I55. The lever I55 is pivoted on a pivot I51, and its left end is attached to a link I55 which in turn is attached to another lever I55 pivoted on a pin I15 adjacent the member I II. The right end of the lever I55 bears against the left end of the whiiiietree I45. When the thermostat I55 which is like that of previous embodiments is in its satisfied position, the electrov 12 end bears against the whiflietree I45 lifting it up to the stop I45 in which position the switch 51 is opened. The right end of whiilietree I45 will of course normally be in engagement with stop I45 because after switch 51 is closed to start the compressor the pressure will fall relatively quickly to permit spring I to raise the right end of the whiiiletree against stop I45. Thus, whenever the thermostat is in its satisfied position, the switch is mechanically held in its open position so that the compressor cannot be cycled by the suction pressure responsive device. It follows, that after the compressor has been stopped it cannot be restarted until there is a demand by the thermostat.

Referring to Figure 6 of the drawings, I have shown another form of my invention which is similar to the embodiment of Figure 5. The controller of Figure 6 comprises a casing I15 and within the casing is mounted a housing I15 within which is an expansible and contractible bellows which is to be connected to the suction line of a refrigerant compressor as in previous embodiments. The bellows actuates a bellows post I11 which has a pointed end engaging in a suitable seat at the mid point of a whiiiietree type lever I15. At the mid point of the whiilietree at the opposite side is connected the operating stem of a snap switch 51 as in previous embodiments. In the present embodiment, the snap switch is closed when the operating stem I19 is pushed inwardly, thatis, downwardly. The ends of the whiii'ietree I15 are slightly enlarged andthe left end has an opening I 55 while the right end has an opening ill, the opening I55 engaging a pin I52 mounted in the casing and the opening "I engaging a pin I55 mounted in the casing, the pins being smaller in size than the openings. Numeral I54 designates a coil spring, the lower end of which is attached to the left end of the whiflietree I15 and the upper end which is attached to a member I55, the member engaging a screw I55 and the screw being adjustable from outside of the casing I15. Numeral I51 designates a similar spring attached to the right end of the whifiietree I15, the upper end of the spring engaging a member I55 which is engaged in screw-threaded relationship with a screw I55 adjustable from outside of the casing I15.

With the controller in the position shown, the whiiiietree has both its ends in their lowermost positions with the pins I5! and I55 which act as stops enga n the upper sides of their respective openings. With the parts in this position,

the switch 51 is closed so as to cause the compressor to operate and to reduce the suction pressure. Spring I54 is adjusted so as to be strongerthan the spring I51, and as the suction pressure is reduced, the bellows within housing I15 begins to collapse or contract and the spring I55 moves the left end of whiiiietree I 15 upwardly so that the pin I52, which acts as a stop, engages the lower side of opening I55. This movement, however, is insuihcient to open the switch which movement requires that the right end of the whiiiietree I 15 to be also moved upwardly before sufficlent movement is imparted to operating stem I15 to open the switch. As the suction pressure continues to fall, (the bellows exerts less switch 31 is again closed. The operation so far.

described is that which takes place without the electromagnetic attachment of my invention.

Numeral I9I designates an electromagnetic device similar to that shown in previous embodiments comprising a winding arranged to attract an armature which is attached to a stem I92. The electromagnetic device is mounted on a bracket-[I93 secured within the casing I15, and the stem I92 is normally biased in a downward direction by a coil spring I94 attached to a portion oflthebracket I93. Numeral I95 designates a lever pivoted to the stem I92 by means of pivot I95. The left end of the lever I95 has a projecting portion I91 forming a cam surface and the lower side of which rests on a top or support I98. Numeral I99 designates a guiding link, one end of which is pivoted to the bracket I93 and the other of which is pivoted on the pivot I95 for guiding the stem I92 in its vertical reciprocatory movements. The electromagnetic device I 9I is controlled by a thermostat I03, the same as in previous embodiments, the thermostat energizing the electromagnetic device in the present embodiment when the thermostat is unsatisfied (bellows expanded). With the parts in the position shown, the electromagnetic device is energized, the thermostat being in unsatisfied position, and with the parts in this position the armature of the electromagnetic device is attracted and raised with the stem I92 pulled to its uppermost position against the bias of spring I94. With the parts so positioned, the lever I 95 is substantially horizontal and the cam portion I91 has no effect upon the whiflietree I18. Under these circumstances, the controller operates normally to cycle the compressor from suction pressure. Now if the thermostat should become satisfled (bellows retracted), the mercury switch deenergizes the electromagnetic device I9I so as to release the armature permitting spring I94 to pull stem I92 downwardly moving lever I95 in a clockwise direction. Upon such movement of lever I95, the cam portion I91 exerts a leverage upon the right end of whiflietree I 18 moving said end upwardly until stop pin I83 engages the lower side of opening I 8|. It will be understood that after the switch 31 has been closed by suction pressure, practically as soon as the compressor starts, the stronger spring I84 will move the left end of whiilietree I18 upwardly as the suction pressure begins to fall. Thus when the right end of whiilietree I18 is moved upwardly by the lever I95, the switch 31 will be moved to open position and will be held in open position as long as the electromagnetic device is deenergized, that is, as long as the thermostat is satisfied. From the foregoing it will be understood that the present embodiment is similar to the previous embodiments but is different as to particular details.

Referring to Figure 7 of the drawings, I have shown a further form of my invention wherein I employ theelectromagnetic attachment, but instead of utilizing it to cause the controller to start the compressor or to prevent the compressor from operating, it changes the control setting of the suction pressure responsive means. The cona knife-edge formed on a member 205 mounted within the casing. The left end of lever 208 is disposed between projections 209 and 201 forming stops, the projections forming part of a bifurcated member 208 mounted within the casing r 200. The lever 203 has an integral arm 209 carrying a pin 2I0 engaged in a slot in the end of a smallswitch carrying lever 2II pivotedon a pin 2I2, the lever 2 having a clip 2I3 in which is carried a mercury switch 2. When the lever 203 moves pivotally, the arm 209 is moved to the right or left, and the pin 2I0 rotates the lever 2I I on its pivot so as to open and close the mercury switch 2I4.

Numeral 2I1 designates a coil spring, the lower end of which is attached to an ear on the lever 203 and the upper end of which is attached to a member 2I8 engaged in screw-threaded relationship with an adjusting screw 2I9 which extends throughout the side wall of the casing 200 and is adjustable from the outside thereof. The spring 2I1 normally urges the lever 203 in a clockwise direction about its pivot. Numeral 220 designates a small lever pivoted at 22I and having an upstanding finger 222 adapted to engage the left end of lever 203. A coil spring 223 is attached to the lever 220 at one end and the other end of the coil spring 223 is attached to a member 224 which is screw-threadedly engaged with a screw 225 which extends through a side wall of the casing 200 and is adjustable from the outside thereof. Stop 201 limits counter-clockwise movement of lever 220.

The electromagnetic device 228 of the present embodiment of the invention is supported on a bracket 221 and includes a winding and an armature 229 carried on the end of a lever 230. The electromagnetic device is controlled by the thermostat I03 as in previous embodiments, the device being energized when the thermostat is in an unsatisfied position. The left end of the lever 230 is erimped at 23I and the crimped portion pivotally engages a knife-edge on the upper side of member 205 previously referred to. Numeral 23I designates a coil spring, the lower end of which engages a boss 232 on the lever 230 and the upper end of which engages a spring retaining member 233, which is attached to an adjusting screw 234 extending from the support bracket 221.

The lever 230 has a downwardly extending finger 235 which is coaxially aligned with bellows post 202 and which engages the lever 203 on the side opposite the bellows post. The spring 23I is a compression spring, the compression of which is adjustable by adjusting the screw 234. From the above description, it is to be seen that the force exerted by spring 23I directly opposes the bellows within the casing 20 I The forces exertedby the spring and bellows are directly in line. Whenever the thermostat I03 is unsatisfied, the electromagnetic device is energized so as to attract the armature 229 moving the lever 230 in a clockwise direction so as to control the spring 23I and move the finger 235 out of engagement with the lever 203. Under these circumstances the spring with the electromagnetic device energised, the controller operates normally as follows. The switch ill is closed causing the compressor to operate, the suction pressure is at an intermediate value and lever'iil is engaging stop ill preventing its further upward movement. As the suction pressured r the bellows within housing ill contracts permitting the coil spring in to move the lever ill in a clockwise direction about its pivot.- As the lever ili moves about its pivot in this manner, arm ill moves to the right causing pin ill to rotate lever ill in a counter-clockwise. direction about its pivot until the mercury switch ill is opened and this occurs at a relatively low predetermined value of suction pressure. The stop ill limits the upward movement of the left end of lever ill. When the compressor has been stopped, the suction pressure rises causing the bellows within housing ill to expand, thereby rotating the lever ill in a counter-clockwise direction against the force exerted by spring ill. During this operation the arm ill moves to the left rotating lever ill in a clockwise direction. As the left end of lever ill moves downwardly, it engages the ilnger iii requiring that the lever iil be moved in a clockwise direction for further downward movement of lever ill. Thus, further expansion of the bellows is by the force exerted by both springs ill and iil. When the suction pressure has risen to a predetermined relatively high value, -the lever ill will be rotated to such a position that arm ill rotates lever ill to a position wherein mercm'y switch ill is closed. The pressure at which mercury switch ill is clowd of course depends upon the tension of spring iil which is adjustable by screw iil inasmuch as this spring must be overcome in order to close the switch. Spring iil is preferably adjusted so that the evaporator oi the system will be defrosted before the switch closes. Screw iil therefore provides an adjustment of the cut-in point of the switch. Only spring ii! is eilective upon the lever ill at the time that the switch isopenedsothatatthistimeonlytheiorceof this spring must be balanced against the force exerted by the bellows. The screw ill therefore provides a separate adjustment of the cut-in point of the switch.

Whenever the thermostat Ill is satisfied, the electromagnetic device iil is deenergised and the partsmaybeinthepositionshowninl 'igure'l. Under these circumstances the bellows within casing ill is directly opposed by the spring ill, and both the cut-in and cut-out points of the switch are raised. That is, with the parts in the position shown with spring ill resisting ex'- pansion of the bellows, the pressure must rise to a predetermined relatively higher value to close the switch. as now assumed, this value depending upon the adjustment of spring ill and correspondingly the switch will open at a higher than normal pressure. The adjustment of spring ill is in practice such that when the electromagnetic device is deenergised the controller will normally be held in the oil pomtion. That is the cut-in point oftheswitchwillberaisedtosuchavalue of suction pressure that normally, when the thermostat is satisfied, the switch will stay in open position until the suction pressure rises. as at present assumed, a predetermined amount above thenormal cut-invalue. Itistobeseentherefore that the present embodiment functions similarly to previous embodiments, in that the thermostat 16 tainthecontrollerintheoflpositiombutinthe preunt t the electromagnetic device raisesboththecut-inandcut-outpointsotthe switch, without positively holding it open.

Referringtol'lgure8otthedrawings,1have shown another modified form of my invention a controller which embodies features oftheembodimentsofl'igureslandlandofthe embodiment of Figure 7. Numeral ill designates a pressure actuatablc device embodying a bellows responsive to auction pressure having a bellowspostillengagingtbemidpointoia whiflletree ill. The ends oi the whiilleh'ee are biiurcated to form flmers ill and ill at oneend and fingers ili and ill at the other end, the tingers forming stops between which are disposed stop pins ill and ill, respectively. One end of the whiiiletree ill is normally urged downwardly byacoilsprlngill andtheotherendisnormally urged downwardly by a coil spring ill. The spring ill is the stronger of the two and of course both may be made adjustable. Numeral l1 designates the snap switch which has been described in previous embodiments, the snap switch having an operating stem ill extending downwardly and being connected to the mid point of whiiiletree ill. The operating stem ill has a horizontally extending pin ill. Numeral ill designates a lever pivoted at ill and having its right end urged downwardly by a coil spring ili. An intermediate point of lever ill rests on the pinillandinasmuchasthepinillisvertically aligned with the bellows post ill, the downward force exerted on lever ill by spring ili directly opposes the force exerted by the bellows responsive to auction pressure. Numeral ill designates an electromagnetic device similar to that of previom embodiments controlled by a thermostat lll also similar to that of previous embodiments. The lever ill has an armature ill at its right end cooperating with the electromagnetic device.

The electromagnetic device ill is energised when the thermostat Ill is \msatisned, and under these circumstances the armature ill is attractedsoastomovetheleverillinacoimterpositionshowmtheswitch l'lisclosedand compressor is operating to reduce the pressure. Inasmuch as spring ill is thanspring ill. the right end of whiilletree hasbeenmoveddownwardlyimtilstoppinil in cat with stop pin ill. suctionpressurehasbeenreduoedto mined value. the left end of linger-ill engagesstoppinill. of lever ill then until linger illstoppinill. Whenthelatteroccurs,theoperatlngstemillwillbemovedupwardlysuilieientlytoclosethesnapswitchl'l andrestartthecompreuor.

when the thermostat Ill sawed.

intherefrigerated compartmenttendstomaintheelccdevioeillisdoanerghsdand the parts assume the positions shown in Figure 8. Under these circumstances the lever 255 is.

hearing against pin 255, and the downward force direction of the switch. The function of the electromagnetic device is substantially the same in-the present embodiment as in the previous embodiment, and normally the additional re- 18 in the bellows within housing 2". The bellows post 252 bearing againstthe whiiiletree 255 has caused its right end to move upwardly against the force of the weaker spring 255 to move the lever 255 upwardly moving its right end away from the stop 255. When the lever 255 engages the stop 212,'the bellows will cause the left end 7 of whiilietree 255 to move upwardly until the sistance provided by the spring 252 is sufllcient to maintain the controller in the off position unless the suction pressure rises to a somewhat higher value.

Referring to Figure 9 of the drawings, I have shown a further modified form of my invention wherein the electromagnetic attachment is applied to another form of controller; In Figure the controller comprises a whiflletree type of lever 255 which is actuated by an expansible' and contractible bellows within a bellows housing l, the bellows having a bellows post 252 bearing against the lower side of the mid point of the whiilletree 255. The bellows is to be connected to the suction pipe of the refrigerant compressor as in previous embodiments. The left end of the whiffletree 255 is biased downwardly by a coil spring 255, and the right end of the whiflletree 255 is biasedv downwardly by a coil spring 255 which is weaker than the spring 255. The coil springs correspond to those of the previous em bodiment and both may be made adjustable. The whiilietree 255 has an upstanding leg 255 at its left end, to which is pivoted a lever 255 by means of a pin 251. At the right end of the whiflietree 255 is an upstanding leg 255 having pivoted thereto a lever 255 by means of a pin 215. Connter-clockwise movement of the whiilletree 255 is limited by a. stop 21Iand a second stop 212. The snap switch 51 has an operating stem 215 with a button 215 on the end of the switch, the stem being in line with a bellows post 252 as shown. The right end of the lever 255 engages the lower side of the button 215 and the left end of lever 255 engages the upper side of the button 215.

Numeral 215 designates another lever pivoted at 215 and arranged to engage a pin 211 at an intermediate point of the lever, the pin 211 extending outwardly from the whliiletree 255 and the said point of lever 215 being in vertical alignment with the bellows post 252. The lever 215 left end of lever 255 engages stop 255. Upon this occurring, lever 255 will be unable to freely rotate on its pivot, and further upward movement of the left end of whiiiietree 255 causes the .leg 255 to rotate the lever 255 about the stop 255 acting as a fulcrum and the right end of lever 255 will move the operating stem 215 of the switch 51 upwardly so as to close the switch and start the compressor. When the compressor starts and the suction pressure begins to fall, the

left end of whiilietree 255 will first move downwardly by reason of spring 255 being stronger until stop 21! is engaged. This action will impart no movementto the operating stem 215 of the snap switch 51. As the suction pressure continues to fall, the right end of whiilletree 255 will move downwardly until the right end of lever 255 is brought into engagement with stop 255. When this occurs, lever 255 will not be able to rotate freely on its pivot, but it will be then rotated is normally biased in a clockwise direction by a coil spring 215. Numeral 215 designates the electrcmagnetic attachment which is the same as in previous embodiments and which is controlled by a thermostat I55. The lever 215 carries an armature 255 at its right end which may be attracted by the windings of the electromagnetic device.

when there is a demand for refrigeration by thermostat I55, the electromagnetic device 215 is energized and armature 255 is attracted to disdevice being inactive to affect the controller when engage lever 215 from pin 211 and to'thereby relieve the control of the effect of spring 215.

With the electromagnetic device 215 energized, the operation of the controller of the present embodiment is as follows: with the parts in the position shown. the switch 51 is open and the .pressure is rising in the suction line and hence in a counter-clockwise direction about the stop 2.55 acting as a fulcrum. The left end of lever v255 engaging button 215 will then pull the operating stem 215 of the snap switch 51 downwardly so as to open the switch. When this occurs, the compressor will be stopped.

Whenever the thermostat I55 becomes satisfied indicating that there is no further need for refrigeration, the electromagnetic device 215 is deenergized and the parts assume the position shown in Figure 5. Under these circumstances, the spring 215 acting on lever 215 imposes a downward force on the whlflietree 255 which is directly in line with the force exerted upwardly through the bellows post 252 by the bellows within housing 2". This downward pressure raises both the cut-in and cut-out points of the switch as in the previous embodiment and is normally sufilcient to keep the switch 51 in an oil position so that when the thermostat is satisfied the compressor is normally maintained out of operation. If, however, the suction pressure should rise to a value determined by the tension of spring 215, the force exerted by the bellows may overcome the spring 215 and operate the whiilletree in the same manner as described above to close the snap switch 51 and restart the compressor. It is to be seen therefore that the present embodiment provides a form of controller for the compressor having separate adjustments of the cut-inand cut-out points of the controlling switch, the electromagnetic device providing an attachment for the controller whereby it is normally maintained in the off position when the thermostat is satisfied and the electromagnetic the thermostat is unsatisfied.

Referring to Figure 15 of the drawings, I have shown another form of my invention embodying a controller which'is very similar to the controller of Figure 4 of the drawings. In Figure 15, numeral 255 designates a housing containing a. bellows responsive to suction pressure and operative to move a bellows post 255 bearing against a lever 251 pivoted at 255. The lever 251 is normally biased in a counter-clockwise direction by I a coil spring 255, and it has an upstanding portion Ill pivoted to a floatinglever lli, the left end of which is movable between stops 2!! and as that of Vrrevious embodiments and is similarly controlled by a thermostat ill. Numeral Ill designates a lever pivoted at ill and having a downwardly extending finger 299 at its left end which bears against the lever 29'! opposite the bellows'post 296, the finger 2" and the bellows post 2" being in vertical alignment. The lever 291 carries an armature Ill at its right end. Numeral lll designates a coiled compression spring which engages the lever 291 to the right of the pivot 298 and which normally urges the lever 2" in a counter-clockwise direction. The thermostat ill energizes the electromagnetic device Zll when the thermostat is unsatisfied, that is, when there is a demand for refrigeration. Under these circumstances, the armature Ill is attracted so as to rotate the lever ina clockwise direction against the force of spring lli so as to disengage finger 299 from the lever 281. When the electromagnetic device is thus energized, the spring SM is inactive to exert any effect upon the controller and the operation is then very similar to that of the embodiment of Figure .4. With the lever ill in the position shown, the suction pressure is at an intermediate value and is rising. As the pressure rises, the lever 2" is rotated in a clockwise direction by bellows post 296 and thus moves the left end of lever 29! upwardly against the force of spring 2". When the left end of lever Ill engages the stop 292, the lever 29! pivots in a counter-clockwise direction about the stop 292 which acts as a fulcrum. The right end of lever Ill then moves the button 194 and operating stem 29! of switch 31 upwardly so as to close the switch and start the compressor. .When the compressor starts, the suction pressure falls causing the bellows within housing ill to contract moving lever ill in a counter-clockwise direction and moving the left end of lever 29l downwardly. when the left end of lever 29! engages the stop 292, lever ill pivots in a clockwise direction about the stop Ill which acts as a fulcrum. The right end of lever 29I now moves downwardly so as to pull downwardly on the button 294 and the operating stem 29! of the snap switch 31 so as to open the switch and stop the compressor.

Whenever the thermostat Ill becomes satisfled, the electromagnetic device 299 is deenergised and the parts assume the positions shown in Figure 10. Under these circumstances, the spring lli exerts downward force through the lever 291 4 and finger 299 which directly opposes the force exerted by the bellows within housing 2" so as to tend to prevent the suction pressure from closing-the snap switch 31. The force exerted by spring lll raises both the cut-in and cut-out points of the switch as in previous embodiments and is normally suilicient to maintain the controller in the of! position when the thermostat is satisfied. However, in the event of the suction pressure rising to a relatively high value determined by the force of spring lli, the bellows within housing Ill may expand sufficiently to close the switch ll and start the compressor in the same manner as described above. From the foregoing, it will be seen that in the present embodiment, an electrom ere is provided a controller with satisfied but which raises the control setting of the controller to a high enough value when the thermostat is satisfied to normally maintain the controller in the off position.

In all of the embodiments of my invention which I have disclosed, the controller has switch operating mechanism which may be operated by a bellows responsive to suction pressure of the compressor. It is to be understood that my invention also comprehends the use of bellows responsive to temperature of the refrigerated compartment for actuating the controller switch and controlling the electromagnetic device by means of a switch responsive to suction pressure. A device which is mechanically actuated in response to the temperature of the refrigerated compartment or the suction pressure may be substituted for the electromagnetic device and arranged to invention which may be made by those skilled in the art but which fall within the spirit and scope of my invention, and therefore my disclosure is not to be interpreted in a limiting sense but only in a representative one. The invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a refrigerating system, in combination, means including an evaporator and a source of refrigerant supply for said evaporator, control means for said source of supply comprising a switch, actuating means for the switch including a device responsive to a condition which is a measure of evaporator temperature, said actuating means being arranged to close said switch at a predetermined value of the condition, means responsive to a condition of a medium affected by operation of the said system. and mechanism associated with said actuating means and controlled by said last condition responsive means,

said mechanism being arranged to close said switch when the condition of the medium attains a predetermined value, said mechanism controlled by the means responsive to the condition of the medium comprising an electromagnetic device operable on the switch actuating means.

2. In a refrigerating system, in combination, means including an evaporator, and a source of refrigerant supply for said evaporator, control means for said source of supply comprising a switch, actuating means for the switch including a device responsive to a condition indicative of evaporator temperature, said actuating means being arranged to close said switch at a predetermined value of the condition, means responsive to a condition of a cooled medium indicative of a need for operation of the system, and mechanism associated with said actuating means and controlled by said last condition responsive means, said mechanism being arranged to close said switch when the condition of the medium attains a predetermined value, said mechanism etic attachment which does not effect the controller whe'n'the thermostat is unasaaasr when the condition of the medium attains said predetermined value. v

3. In combination, an electric snap switch, a

condition responsive device, mechanical connections between said device and switch by whichsaid device normally opens and closes said switch solely upon changes in the condition to which it responds to spaced predetermined values, additional mechanical means including stress limitswitch to cut-out position in 22. to move said switch to cut-out position independent oi. the other two responsive devices and to permit it to be moved to cut-in position it'said other two devices are in their cut in positions, and electrically operated means to move said response to said air temperature responsive means.

ing means operable to a position to open said I switch and prevent closing of said switch upon a change in said condition to a value at which said condition responsive device would normally close said switch, and electromagnetic means in control of said mechanical means.

4. In combination, an electric snap switch, a condition responsive device, mechanical connections between said device and switch by which said device normally opensand closes said switch solely upon changes in the condition to which it responds to spaced predetermined values, additional mechanical means including spring means operable to a position to bias said switch to one of its circuit controlling positions to thereby prevent operation of said switch to the other of its circuit controlling positions even though there is a change in said condition to the value at which said condition responsive device would normally operate said switch to said other of its circuit controlling positions, the extent of said bias being limited by said spring means, and electromagnetic means in control of said mechanical means.

5. In combination, an electric snap switch, means-to open and close said switch including a lever which must be moved to a first position to open said switch and must be moved to a second position substantially spaced from said first position to close said switch, a condition responsive device for operating said lever to its first position at one value of the condition to which it responds and for operating said lever to its second position at a different value oi said condition, additional means including a spring operable to urge with a predetermined force said lever towards one of its positions, and electromagnetic means in control of said last-named means.

6. In combination, an electric snap switch, means to open and close said switch including a lever which must be moved to a first position to open said switch and must be moved to a second position substantially spaced from said first position to close said switch, a condition responsive device for operating said lever to its first position at one value of the condition to which it responds and for operating said lever to its second position at a diiierent value of said condition, spring means operable to urge said lever towards one of said positions, and electromagnetic means operable to render said spring means eil'ective and ineffective.

7. In a refrigerant system' controller, a switch in circuit with a refrigerant compressor motor, a pair of devices responsive respectively to air temperature in the space being refrigerated and to low side refrigerant ressuresaid responsive devices each being operable independent oi. the other one to move said switch to cut-out position, both of said responsive devices being associated 8. Ina refrigerant system controller, a switch in circuitwith-a refrigerant compressor motor, a first device responsive topressure in the low side of the refrigerant system, a second device responsive to pressure in the high side of the refrigerant-system, a third device responsive to the temperature of air in the space being refrigerated by said refrigerant system, said first. second and third devices being operatively connected with said switch to effect cut-out thereof upon movement of any of the three devices to its cut-out position and to efi'ect cut-in oi the switch only when all three devices are in their cut-in positions, said third device including an electromagnet for moving the switch to cut-out position, and a thermostat in circuit therewith and located in the space being refrigerated. '9. In control apparatus for a refrigerating sy tem comprising, in combination, switch means, means including a condition responsive device for actuating said switch means, and a mechanism associated with the said actuating means, said mechanism including an electromagnetic device and means controllable thereby, the said controllable means being operable to bear against the said actuating mean to oppose actuation of the said switch means by said condition responsive means, the said electromagnetic device being capable when energized or holding the said controllable means in an ineil'ective position.

10. In control apparatus for a refrigerating system comprising, in combination, switch means,

with said switch so that both must normally be means for actuating. said switch means including a condition responsive device, said actuating means being arranged to operate said switch means to cut-in. and cut-out positions at predetermined values of the condition to which the said device responds, and mechanism for exercising control over said switch means including an electromagnetic device operable on a portion of the switch actuating means, said electromagnetic device either being ineifective to control operation of the said switch means or operative to overpower the said pressure responsive device and assume primaryacontrol of said switch means.

11. In refrigerating control apparatus, in combination, switch means, actuating means for said switch means including a condition responsive device, said actuating means being operative to close the said switch means at a predetermined relatively high value of the condition to which said device responds and operative to open the said switch at a predetermined relatively low value of the said condition, and auxiliary mechanism associated with the said actuating means, said mechanism comprising an electromagnetic device arranged to obstruct closing of the said switch means upon a predetermined state of energization ofthe said electromagnetic device.

12. In refrigerating control apparatus, in combination, switch means, actuating means for said said switch means, said mechanism comprising a two-position device including an electromagnet and means controlled thereby, said means controlled thereby being operative in one position to obstruct operation of the said switch means by said actuating means and ineffective in its other position to ailect the operation of said switch means, the state of energisation of said electromagnet determining which of the two positions will be assumed by the said controlled means.

13. In control apparatus for use with a condition responsive control device including switching means and having an actuating bar, comprising, in combination, an electromagnet, support means for the said electromagnet, lever means pivotally mounted to said support means and including an armature portion for meeting with the said electromagnet, means also including an elongated portion adapted to bear against and to exert pressure on means such as the aforesaid actuating bar, and spring means between said support means and said lever means eflective to rotate said lever means relative to said support means so that the said elongated portion may exert pressure on means such as the said actuating bar when the said electromagnet is deenergized but of such strength that the electromagnet can, when suitably energised, move the said armature portion into anattracted position against the force of said spring and prevent the said elongated portion from exerting the said pressure.

saidmeansbeingnormaliymtivetociolesaid switch atone value ofsaidconditionandtoopen the said switch at adiii'erent value of said condition; andauxiliarymechanismoperativeonsaid 14. In a refrigerating control actuator, an auxiliary device comprising, in combination, an electromagnet, a support means for the said magnet, a lever means pivotally mounted on said support means, said lever means including an elongated actuator portion, an armature portion and an extended portion, said armature portion being adapted to be attracted by the said electromagnet, spring means connected between the said extended portion of the lever means and the said support means for urging said armature portion away from the said electromagnet, the said spring 4.

16. In refrigerating control apparatus, in combination, a switch; means including a condition responsive device for actuating the said switch, said means being normally operative to close said switch at one value 01' said condition and to open the said switch at a diilerent value of said condition; and auxiliary mechanism for changing the values at which the said condition responsive device operates the said switch, the said mechanism comprising a movable portion, spring means for moving said portion in one direction.

anism operative on said actuating means for opening saidswitch regardless of said condition responsive device and for opposing the closing oisaidswitchbythesaiddevicasaidmech; anism including a movable member, a spring means, and an electromagnet, the said movable member being operative to switch opening position by said spring means and being retractable by said electromagnet.

ALWIN n. mrw'rou,

REFERENCES CITED The following references flle of this patent:

UNITED STATES PATENTS Number Name Date 1,162,071 Jordan Nov. 30. 1915 1,560,932 Eaton Nov. 10, 1925 1,667,001 Gray et al. Apr. 24, 1923 1,703,235 Heath Feb. as. 1929 1,722,768 Schnetaler July 30,1929 1,723,038 Burstyn Sept. 10. 1929 1,764,374 White June 17, 1930 1,802,679 I Bpeiser Apr. 23, 1931 1,908,193 Btannard May. 9,1933 1,979,779 Tobin Nov. 6, 1934 2,014,386 lamb Sept. 17, 1035 2,028,077 Parsons Jan. 14, 1936 2,080,169 Dillman May 11, '1937 2,osi,s53 Dillman m 25; 19:7 2,090,526 Eaton l Aug. 17, 1937 2,138,509 Raney Nov. 29, 1933 2,165,518 Stolz July 11, 1939 2,139,381 llcGrath rec. 6. 1940 2,213,505 Raney 1 Sept. 3, 1940 2,216,589 Grooms Oct. 1, 1940 2,218,944 Wolfert Oct. 22. 1940 2,226,297 Shangenberg Dec. 24, 1940 2,247,060 Levine June 24, 1941 2,270,353 Bpurck Jan. 20, 1942 2.273.127 McGoldrick Feb. 17, 1042 2,308,261 Bartlett et a1. Jan. 12, 1943 2,308,313 Shaw Jan. 12, 1943 2,362,207 Kuhn Nov. 7, 1044 areoirecordinthe 

